Synthesis of Macroporous Poly(styrene-co-divinylbenzene) Microparticles Using n-Heptane as the Porogen: Quantitative Effects of the DVB Concentration and the Monomeric Fraction on Their Structural Characteristics

Macroporous Polymer⁻Protein Hybrid Materials for Antibody Purification by Combination of Reactive Gelation and Click-Chemistry

Clickable core-shell nanoparticles based on poly(styrene-co-divinylbenzene-co-vinylbenzylazide) have been synthesized via emulsion polymerization. The 38 nm sized particles have been swollen by divinyl benzene (DVB) and 2,2'-azobis(2-methylpropionitrile) (AIBN) and subsequently processed under high shear rates in a Z-shaped microchannel giving macroporous microclusters (100 µm), through the reactive gelation process. The obtained clusters were post-functionalized by "click-chemistry" with propargyl-PEG-NHS-ester and propargylglicidyl ether, yielding epoxide or NHS-ester activated polymer supports for bioconjugation. Macroporous affinity materials for antibody capturing were produced by immobilizing recombinant Staphylococcus aureus protein A on the polymeric support. Coupling chemistry exploiting thiol-epoxide ring-opening reactions with cysteine-containing protein A revealed up to three times higher binding capacities compared to the protein without cysteine. Despite the lower binding capacities compared to commercial affinity phases, the produced polymer-protein hybrids can serve as stationary phases for immunoglobulin affinity chromatography as the materials revealed superior intra-particle mass transports.

A novel route for synthesis of cross-linked polystyrene copolymer beads with tunable porosity using guar and xanthan gums from bioresources as alternative synthetic suspension stabilizers

Cross-linked polymer beads with different cross-linking agent loading were prepared by carrying out cross-linking suspension copolymerization of styrene-divinylbenzene (St- DVB) monomers using guar gum (GG) and xanthan gum (XG) from bioresources as eco-friendly suspension biopolymer stabilizers in the presence of non reactive diluents. The effects of GG and XG as suspension biostabilizers on the characteristics of the styrene copolymer beads were investigated regarding thermal properties, porosity characteristics, solvent swelling ratio, and surface morphologies using TGA, DSC, XRD, SEM, BET analyses. Spherical and regular beads with smooth surface were produced and the average particle size was in the range 170-290 μm (50-80 mesh size). The porosity characteristics of the produced beads including surface area and pore volume were in range 0.45 m2/g and 32-45 ml/g, respectively. Overall, the present article provided a novel route to prepare cross-linked polystyrene copolymer beads with tunable porosity suitable for catalyst support.

High porosity microspheres with functional groups synthesized by thiol–yne click suspension polymerization

We employed a combination of thiol–yne click polymerization and suspension polymerization for the synthesis of porous epoxy-functionalized polymeric microspheres.

Synthesis of macroporous polymer particles using reactive gelation under shear

By combining elements from colloidal and polymer reaction engineering a new approach toward macroporous, mechanically robust polymer particles is presented, which does not require any porogenic additives. Specifically, aggregation and breakage in turbulent conditions of aggregates originating from fully destabilized primary latex particles is applied to produce compact, micrometer-sized clusters. Post-polymerization of monomer introduced initially to swell the primary particles is imparting mechanical rigidity and permanence to the internal structure. The resulting microclusters exhibit an internal porosity on the order of 70% and relatively broad pore size distribution, with exceptionally large pores, ranging from about 50 nm to 10 μm in diameter. These particulate microclusters, produced via reactive gelation under shear, are fractal objects with fractal dimension around 2.7, as opposed to the more open fractal structure of a monolith produced via stagnant reactive gelation, with fractal dimension of 1.9. Such macroporous particles are thought to be useful in applications requiring pores on the micrometer scale, e.g., in the chromatography of biomolecules or for packing beds perfusive to convective flow.

Preparation of a novel magnetic microporous adsorbent and its adsorption behavior of p-nitrophenol and chlorotetracycline

A novel method for fabricating hypercrosslinked magnetic polymer beads with improved acid resistance was developed. Magnetite nanoparticles were covered with tetraethoxysilane and vinyltriethoxysilane, followed by co-polymerization and post-crosslinking. The resulting M150 beads were highly stable at pH ≥ 2 and were superparamagnetic, with a saturation magnetization of 3.1 emu/g. M150 exhibited a specific surface area of 1022.4m(2)/g and an average pore width of 2.6 nm. The adsorption of p-nitrophenol and chlorotetracycline (CTC) onto M150 and the commercial non-magnetic resins NDA 150 and XAD-4 followed both pseudo-first-order and pseudo-second-order equations. M150 displayed much faster kinetics than the other resins because of its small particle size and abundant macropores. The adsorption isotherm of p-nitrophenol onto the three resins fitted the Freundlich equation (R(2)>0.98), whereas CTC adsorption was better described by the Langmuir isotherm. p-Nitrophenol adsorption was optimal at pH ≤ 4, whereas CTC adsorption was optimal at pH 5-6. All three sorbents showed high reusability for p-nitrophenol adsorption. XAD-4 demonstrated the highest reusability for CTC. The CTC adsorption capacities of M150 and NDA150 decreased by 12.42% and 20% after 10 adsorption-desorption cycles, respectively.

Facile preparation of hierarchically porous polymer microspheres for superhydrophobic coating

A facile method, i.e., nonsolvent assisted electrospraying, is proposed to fabricate hierarchically porous microspheres. The pore size on the microsphere surface ranges from a few tens to several hundred nanometers. Thermally and nonsolvent induced phase separation as well as breath figure is responsible for the formation of the hierarchical structures with different nano-sized pores. The nonsolvent could not only induce phase separation, but also stabilize the interface between the droplet and air, which can prevent the droplet from strong deformation, and is therefore beneficial to the formation of regular and uniform microspheres. On the other hand, solvent evaporation, polymer diffusion and Coulomb fission during electrospraying influence the morphology of finally obtained products. In this paper, the influence of polymer concentration, the weight ratio between nonsolvent and polymer and the flowing rate on the morphology of the porous microsphere is carefully studied. The hierarchically porous microsphere significantly increases the surface roughness and thus the hydrophobicity, and the contact angle can reach as high as 152.2 ± 1.2°. This nonsolvent assisted electrospraying opens a new way to fabricate superhydrophobic coating materials.

One-pot synthesis of highly folded microparticles by suspension polymerization

A facile method of preparing highly folded cross-linked polymeric microparticles has been developed via one-pot suspension polymerization under high-speed homogenization. The wrinkles result from the evaporation of solvent in the cross-linked microparticles. The effects of microparticle cross-linking density and solvent on the polymer have been studied in detail. It was found that a medium cross-linking density (DVB/St = 0.5 by weight) is optimal for producing the most folded surface and the higher the solvent content, the deeper the surface wrinkles. This method is very simple and in principle can be applied to produce wrinkled microparticles with other chemical compositions.